The present invention relates to instrumentation, and more particularly, to improvements in membrane panels for instruments.
Laminated graphic plastic control panel assemblies are often utilized in instruments in the electronic test equipment, bio-medical, computer, telecommunication and machine tool, and other industries. Such assemblies often include membrane switches which are responsive to external forces to provide an electrically conductive coupling between two terminals. Typically, the switch includes three stacked flexible layers in the panel, where the opposing surfaces of the outer layers include conductive patterns which include overlapping portions and the middle layer includes a void region between the overlapping portions. Conventional membrane panel assemblies, with or without switches, typically include graphic plastic overlays which are bonded to membrane switches which are, in turn, bonded to a rigid sub-panel.
In the prior art, the known panel assemblies are passive, including no electronic circuitry other than conductive patterns, but are often adapted to interface with electronic circuitry. Often, the panel assemblies include light transmissive regions, such as holes, which are adapted for placement over an external light source to provide an illuminated display.
However, all such external circuitry and light sources place restrictions on the utilization of such panel assemblies, in terms of positioning (for example, with respect to an external light source) in the instrument to which the panel assembly is attached. Moreover, the various circuitry for the functions must necessarily be remote from the panel itself.
Accordingly, it is an object of the present invention to provide an active membrane panel.
It is another object to provide a membrane panel which includes integral electronic components.
Another object is to provide a membrane panel having integral illuminating means.